Arc welding head



Feb. 3, 1942.

J. E. ANDERSON ARC WELDING HEAD Filed Nov. 28, 1940 Fig'- i. I I 56 l|2o I f sa 1s es 2s 26 lz- 44' i L 27 24 y 2l l 5 4| ,8 22 34 eff 42,Iwverwtofz Jaspe` E Andersom.,

His Attofvwey.

Patented Feb. 3, 1942 ARC WELDING HEAD Jasper E. Anderson, Saugus,Mass., assignor to General Electric Company, a corporation of New York-Claims.

l My invention relates to an improved electrode feeding mechanism forautomatic arc welding heads.

Automatic arc welding heads are usually employed for repetitive weldingoperations especially where the seams to be welded are of relativelysimple contour such as circles or straight lines. IThese welding headsembody an electrode feeding mechanism which is operated by ay motorforming part of a control system. The control systems usually employedembody means which is responsive to an electrical characteristic of thewelding circuit and which functions to operate the motor of the weldinghead and the electrode feeding mechanism driven thereby to feed anelectrode to and from the work to strike and thereafter maintain awelding arc. c

Due to variations in sizes of electrodes required for various weldingoperations, some posed pairs of feed rolls are geared together in orderto increase their tractive effort on the electrode which they engage andfeed, the gearing interconnecting the feed rolls usually works at adisadvantage due to the imperfect meshing of the gears resulting 'fromthe adjustable spacing of the feed roll shafts. This adjustment of thespacing of the feed roll shafts also makes it difcult, ifA notimpossible, properly to lubricate the gears and to shield them from thedust and dirt almost always present in welding shops.

All the advantages resulting from a fixed spacing of the feed rollshafts may be obtained by using beveled feed rolls as disclosed andclaimed in my United States Letters Patent 2,170,673 of August 22, 1939,for Wire-feedingdevice. Although the arrangement of this patent isadmirably suited for feeding bare or lightly coated electrodes, it isnot satisfactory in every respect for feeding heavy coated electrodesfrom a continu-- ous coil. For feeding heavy coated electrodes, feedrolls ofrubber or other similar elastic material are required in orderto make a substantial engagement with and prevent damage to the elec-Appucation November 2s, 1940, serial No. 367,559

trode fluxxcoating which is frangible and consequently incapable ofsustaining localized pressure without cracking or crumbling from theelectrode.

It is an object of my invention to provide an electrode feedingmechanism for arc welding heads in which the proper adjustment fordifferent sizes of electrodes is obtained by adjusting the diameters ofexpansible feed ,rolls which are positioned opposite one another andmounted on and rotate with a pair of shafts spaced from one another by afixed distance. y

It 'is also an object of my invention to provide an electrode feedingmechanism embodying feed roll shafts spaced from one another by a fixeddistance, rubber feed rolls or tires mounted on these shafts, and meansfor adjusting the diameters of these feed rolls or tires. Such amechanism is admirably suited for feeding heavy coated electrodes ofdifferent sizes as well as for feeding bare and lightly coatedelectrodes.

Further objects of my invention will become apparent from the followingdescription of one embodiment thereof illustrated in the accompanyingdrawing.

In this drawing Fig. 1 isa front view of the electrode feeding mechanismof an automatic arc welding head embodying my invention; Fig. 2 is aside view thereof with parts sectioned along the line 2-2 of Fig. 1;Fig. 3 is a plan view thereof with parts sectioned along the line 3-3 ofFig. l; Figs. 4 and 5 are views illustrating the adjustment of theelastic feed rolls for engaging electrodes of different sizes; and Fig.6 is a sectional view along line 3-3 illustrating in greater detail theconstruction of the feed rolls and of the means employed for adjustingtheir diameters to vary the spacing of their treads for electrodes ofdifferent sizes.

As shown in the drawing, two pairs of feed rolls IIJ, II are mounted onthe ends of shafts I2 andIl which project from a gear box I4. This gearbox is cylin'drical in shape and secured in a cylindrical seat within ahousing I5 by a screw I6. One end of housing I5 is bolted to and closesone end of a housing I1 whose other end is closed by a plate I8.

The armature shaft I9 of a motor 20 mounted l ferred to. One end ofshaft 23 also extendsthrough housing I5 into' gear box I4. This end ofthe shaft is supported in a ball bearing 28 mounted in'the inner or backwall of the gear box.

A spur gear 21 mounted on the end of shaft 23 which is located withingear box I4, meshes with and drives eachv of two gears 28 which ismounted on and imparts rotation to each of the two axles I2 for each ofthe feed rolls I0 of the two pairs of feed rolls III, II.y Each gear 28also meshes with a gear 29.which is mounted on and imparts rotation toeach of the shafts I3 for each of the feed rolls II of the two pairs offeed rolls I0, II. Each of the shafts I2 and I3 of each pair of shaftsis spaced from` one another by a fixed distance determined by theirsupporting ball bearings 38, 3|, 32 and 33 which are located in thefron't and back walls of gear box I4. This spacing is that determined bythe proper meshing of gears 28 with gears 29. Gears 28 are also properlyspaced from gear 21 so that these gears properly mesh with one another.

Gears 21, 28 and 29 are totally enclosed within gear box I4 which may befilled with a high temperature grease introduced therein through anormally plugged filler hole in its front wall. In like mannerl worm 2l,worm wheel 22, bearings'24 and 25, and shaft 23 in housing I1 arelubricated with grease supplied to this housing through a `breatheropening therein. A packing 34 surrounding shaft 23 where it passes intohousing I prevents loss of lubricant from housing I1 into housing I5.Lubricant which may leak from gear box I4 is also kept out of housing I1by packing 34.' This leakage lubricant is also prevented frompassingbetween gear bor Ill and its seat in housing I5 by the use of aheavy grease in grooves 35 located in the side walls of the seat. Apacking 38 between the gear bon and its seat in housing I i5 may also beprovided` for preventing leakage of lubricant from this housing.

Feed rolls III and I I may be made of an elastic material such asrubber. such as used in automobile tires is employed since this givesthe necessary wear resisting qualities to the feed rolls. These feedrolls are essentially tires mounted for rotation with shafts I2 and I3by being attached thereto through keys 337.1

These keys also engage keyways in side plates or shrouds 38 and 39 whichfrictionally engage opposite sides of the feed rolls. The outer porntions of side plates 38 and 39 which engage the side surfaces of thefeed rolls are also provided with a plurality of circumferentiallyspaced teeth I0 which engage and prevent rotation of the feed rollsrelative thereto. It will thus be seen that the feed rolls are caused torotate with the shafts on which they are mounted by being both directlykeyed to these shafts and indirectly keyed thereto through side plates38 and 39.

Means are also provided for applying pressure to the sides of the feedrolls to deform them and thus control their diameters and consequentlythe spacing of their treads. This is accomplished by controlling thespacing of sideplates 38 and 39 through the adjustment of screws 4Iwhich are threadedinto the ends of shafts I 2 and I3. The heads of thesescrews engage washers 4i! which bear against side plates 38.Consequently, by adjusting screws 4I pressure is applied between sideplates 38 and 39 through the agency of washers 42 and shafts I2 and I3whose inner ends are headed and transmit pressure through the innerraces of bearings 30, 3I, 32 and 33, gears 28 and 29 and the spacingring between Preferably a rubber these gears and the ball bearingspreviously mentioned to Washers 43 which engage side plates 39. Bytightening screws 4I the feed rolls are compressed and deformed in amanner to in crease their diameters. In making this adjustment the feedrolls should be calipered to insure that they are al1 adjusted to thesame diameter. This will avoid excessive wear of the feed rolls andtheir drive as well as prevent unnecessary loading of their drivingmotor 2li.

In Figs. 4 and 5 two adjustments of the feed rolls have beenillustrated. In Fig. 4 the treads of the feed rolls have been advancedtoward one another a sufilcient distance to engage and drive a smallersize electrode than is shown in Fig. 5 where the feed rolls have notbeen expanded beyond the diameter of their side plates.

Itisthus apparent that by providing expansible feed rolls whosediameters are adjustable, al1 the advantages resulting from a fixedspacing of the driving shafts for these feed rolls may be obtained in anautomatic arc welding head which is suitable for feeding electrodes ofvarious sizes. The electrodes may be bare, lightly coated or heavilycoated with fluir.

These expansible feed rolls and their :adjustment also simplify theconstruction of the welding head making it possible more readily toadapt other adjusting devices thereto. Thus, for ex.

ample, the arc welding head illustrated in the drawing may be adjustedVabout a hinge pin 4t through the agency of an arm 45 and an adjustingscrew 4t. The Welding head is supported for rotation about this hingepin through the agency of lugs 41 which form part of the front wall ofgear box Ill. This hinge pin is held against rotan tion in lugs 48 of asupporting bracket di?. @ne end of arm 45 is provided with a clamp 5twhich when closed by tightening nut 5i firmly engages hinge pin l4t andits other end is provided with an opening for adjusting screw 4t. Oneend of this adjusting screw is supported for rotation and a slightswinging movement relative to arm. but is immovable lengthwise relative'thereto. The other end of this adjusting screw 4t threaded transverselythrough an opening in a cylindrical nut 52 which is mounted for rotationin a bracket 53 which is attached to housing I5 oi' the welding head. Ahand wheel 54 is provided for rotating the adjusting screw 4t. It willthus y be seen that by turning screw 46 the welding head may be swungabout hinge pin 4t to provide a cross adjustment thereof relative to theseam being welded. This particular adjusting mech anism is `describedand claimed in. United States Letters Patent 2,250,219 Verni J, Chapmangranted July 22, 194i and assigned to the same assignee as the presentapplication.

The electrode 55 above referred to is directed 'between feed rolls Iii,II by a guide 56 mounted in the upper hinge lug 41 of gear box I4. Thiselectrode may be supplied from a reel supporting a continuous coilthereof. It is of course apparent that many modifications may be made ofthe electrode feeding mechanism above described. For example, myinvention is not limited to the use of pairs of elastic feed rolls whichare directly mounted on and attached to their feed shafts. Any form ofexpansible feed roll which is suitably supported on its drive shaftthrough an adjusting mechanism which is-capable of controlling itsdiameter may be used alone or in pairs as a substitute for theparticular`arrangement illustrated and described. Furthermore, instead of usingThus, while I have shown and described but one embodiment of myinvention, it will be understood that I intend to cover by the appendedclaims all modifications of my invention which fall within the truespirit and scope thereof.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An arc welding head comprising a pair of shafts spaced from oneanother by a fixed distance, means for rotating at least one of saidshafts, an expansible feed roll forming one of a pair of feed rollsmounted opposite one another on said shafts, and means for adjustablyvarying the diameter of said expansible feedv roll to control itsdriving engagement with electrodes of different sizes positioned betweensaid feed rolls.

2. An arc welding head comprising a pair of shafts spaced from oneanother by a fixed distance, means including gears mounted on saidshafts for rotating them in opposite directions,

va pair of expansible tires of elastic material mounted opposite oneanother on said shafts for rotation therewith, and means for adjustingthe expansion of said tires to control their driving engagement withelectrodes` of different sizes positioned therebetween.

3. An arc Welding head comprising a pair of shafts spaced from oneanother by a fixed distance, means for rotating at least one of saidshafts, a pair of expansible feed rolls mounted opposite one anotherY onsaid shafts for rotation therewith and having treads spaced from oneanother and adapted to making a driving engagement with an electrodepositioned therebetween, and means for adjusting the expansion of saidexpansible feed rolls to vary their diameters and the spacing lof theirtreads for electrodes of different sizes.

4. An arc Welding head comprising a pair of shafts spaced from oneanother by a fixed distance, means including gears mounted on saidshafts for rotating them in opposite directions, a pair of rubber feedrolls mounted opposite one another on saidf shafts for yrotationtherewith and having spaced treads adapted to making a drivingengagement with an electrode positioned therebetween, and means forapplying an adjustable clamping pressure to the sides ,of said feedrolls to control through deformation their diameters and the spacing oftheir treads for electrodes of different sizes positioned therebetween.

5. An arc welding head comprising a totally enclosed gear box, a pair ofparallel shafts supported in fixed relationship relative to one anotherin said gear box and having corresponding end portions projecting fromone wall of said gear box, means including gearing in said gear box forrotating said shafts in opposite directions, elastic feed rolls mountedopposite one another on said end portions of said shafts for rotationtherewith, side plates keyed. yto said end portions of said shafts onopposite sides of said elastic feed rolls, and means for applying an-adjustable clamping pressure through said side plates to the sidesL ofsaid elastic feed rolls and consequently controlling throughldeformation the diameters of said feed rolls.

JASPER E. ANDERSON.

